The invention is directed to a process for the production of a co-stabilizer from pentaerythritol for the stabilization of vinyl chloride resins, especially polyvinyl chloride.
Polyvinyl chloride (and other vinyl chloride resins) are discolored by the action of light and especially at elevated temperatures, such as occurs in the shaping and process of polyvinyl chloride (and other vinyl chloride resins). To reduce or avoid this effect there are added stabilizers to the polyvinyl chloride (or other vinyl chloride resins). In many cases it is necessary to use co-stabilizers in order to increase and supplement the effect of the stabilizers.
It is known to add as a stabilizer for polyvinyl chloride (and other vinyl chloride resins) metal salts or their mixtures, among others the calcium, strontium, barium, zinc, cadmium, or lead salts of fatty acids and as a costabilizer to use organic phosphites, see Leistner U.S. Pat. No. 2,564,646, the entire disclosure of which is hereby incorporated by reference and relied upon. It is also known to employ as stabilizers mixtures of calcium or zinc benzoate together with mixtures of the calcium or zinc salts of the fatty acid mixtures present in natural fats and oils and to add sorbitol as a costabilizer, Kauder U.S. Pat. No. 3,004,000, the entire disclosure of which is hereby incorporated by reference and relied upon.
As stabilizers there are also employed iron compounds such as iron sulfate and as costabilizer polyhydric alcohols such as pentaerythritol, trimethylolpropane, dipentaerythritol and tripentaerythritol, Buckley U.S. Pat. No. 3,142,659, the entire disclosure of which is hereby incorporated by reference and relied upon. The disadvantage is, particularly with using polyhydric alcohols as costabilizers, that they cannot be homogeneously worked into vinyl chloride resins, e.g. polyvinyl chloride, or at best can only be worked in with considerable difficulty.
Besides it is known to use as stabilizers metal salts, namely calcium or zinc stearate or their mixture and as costabilizer to add a mixture of pentaerythritol and trimethylolpropane and in a given case, other polyhydric alcohols such as dipentaerythritol, tripentaerythritol, neopentyl glycol, trimethylolethane, mannitol, sorbitol or glycerine which are obtained by melting together the pentaerythritol with these materials and pulverizing the solidified melt (German OS No. 2,356,625, the entire disclosure of which is hereby incorporated by reference and relied upon). The thus prepared costabilizer indeed can be homogeneously worked into the polyvinyl chloride but must be used in a relatively large amount for the production of sufficient activity.